Wu Jiun-Yan, Liao Jen-Hung, Shieh Chwen-Jen, Hsieh Feng-Chia, Liu Yung-Chuan
Department of Chemical Engineering, National Chung Hsing University, 145 Xingda Rd., South Dist, Taichung 40227, Taiwan.
Department of Chemical Engineering, National Chung Hsing University, 145 Xingda Rd., South Dist, Taichung 40227, Taiwan; Biopesticides Division, Taiwan Agricultural Chemicals and Toxic Substances Research Institute, Council of Agriculture, Taichung 41358, Taiwan.
J Biosci Bioeng. 2018 Nov;126(5):630-635. doi: 10.1016/j.jbiosc.2018.05.002. Epub 2018 Jun 19.
In this study, the precursor effect for iturin A production was quantitatively analyzed. A strain identified as Bacillus amyloliquefaciens BPD1 (Ba-BPD1) was selected due to its ability to produce iturin A. The enhancement of iturin A production in a submerged culture was tested using various additives, including palmitic acid, oils, and complex amino acids. Among these, complex amino acids triggered the highest yield at 559 mg/L. The respective amino acids that contribute to the structure of iturin A were used as precursors. In fact, it was found that the addition of l-proline, l-glutamine, l-asparagine and l-serine could improve iturin A yield in the defined medium. However, during the kinetic analysis, all the amino acids exhibited a lower saturation level than l-serine, which exhibited a high saturation level at 1.2% resulting in an iturin A yield of 914 mg/L. In contrast, a negative effect was observed following the addition of l-tyrosine. To analyze the kinetic behavior of l-serine, three kinetic models were adopted: the kinetic order equation, the Langmuir kinetic equation, and a modified logistic equation. The regression results showed that the modified logistic model was the best fit for the kinetic behavior of l-serine as the major precursor, which could be further referred to the biosynthesis pathway of iturin A. Among the proposed processes for iturin A production, this study achieved the highest iturin A levels as a result of the addition of precursors.
在本研究中，对伊枯草菌素A产生的前体效应进行了定量分析。由于其产生伊枯草菌素A的能力，选择了一株被鉴定为解淀粉芽孢杆菌BPD1（Ba-BPD1）的菌株。使用包括棕榈酸、油和复合氨基酸在内的各种添加剂，测试了在深层培养中伊枯草菌素A产量的提高情况。其中，复合氨基酸引发的产量最高，为559毫克/升。构成伊枯草菌素A结构的各个氨基酸被用作前体。事实上，发现在限定培养基中添加L-脯氨酸、L-谷氨酰胺、L-天冬酰胺和L-丝氨酸可以提高伊枯草菌素A的产量。然而，在动力学分析中，所有氨基酸的饱和水平都低于L-丝氨酸，L-丝氨酸在1.2%时表现出高饱和水平，导致伊枯草菌素A产量为914毫克/升。相比之下，添加L-酪氨酸后观察到负面影响。为了分析L-丝氨酸的动力学行为，采用了三种动力学模型：动力学级数方程、朗缪尔动力学方程和修正逻辑方程。回归结果表明，修正逻辑模型最适合作为主要前体的L-丝氨酸的动力学行为，这可以进一步参考伊枯草菌素A的生物合成途径。在提出的伊枯草菌素A生产工艺中，本研究由于添加前体而实现了最高的伊枯草菌素A水平。
